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Roubo Joinery Bowsaw Prototype – Plate Anchors

Before I got too deep into making the “bow” of the bowsaw I realized I needed to work out the details of how exactly the saw plate was to be anchored to the bow frame.  Given the robustness of the saw plate from Bad Axe and the illustrations and commentary from Roubo I knew this was not a casual thing.  The amount of tension required to make the saw plate perform well was considerable given the dimensions of the plate, so the anchors for the plate had to be able to withstand the force requisite for making it function well.  And, given the likelihood that any user of such a saw as this might well want to swap out the plate from one utility to another, taking advantage of varying plates that could be available.  So, the fitting of the plate to the frame needed to be not only exceedingly stout but also easily reversed or swapped-out.

The clue to the preferred manner of fixing the plate within the bow frame was pretty clearly described by Roubo in his commentary to Plate 12.  While the simplest method would be to simply drive a pin through the foot of the bow frame and the end of the plate, there was and is a better way.  And he tells us how to do it.

There is still another way to attach the blade in the saw, which is to use stirrups, which are pieces of sheet or flat iron that you fold into the form of a “t”, and that you attach to the two ends [of the blade into the stirrup] with a single nail the same way as above. These are then inserted into grooves in each of the arms, which you take care to fasten tight enough to hold them. This method is very good because the stirrups holding the arms from their back sides make full use of the arms’ strength, without which they might split, and you only use one nail to hold the blade at each end because if there were two it would prevent even blade tension, figures 11 & 12.

I took this information/description and started running with a couple of changes.  First, the folding of bar stock into the “T” was not possible with the material I had on hand, although it might be fine with lighter steel flat stock like 1/32″ or 1/16″.  I didn’t have that (nor did the local fabrication shop) and I was too impatient to wait for some to be shipped to me.  Second, the plates supplied by Bad Axe have two bolt holes, which I believe are necessary to house fittings strong enough to tension the plate.  Still, I really liked the concept of a “T” shaped stirrup to affix the plate in the frame.

So instead of folding thin flat stock for this purpose (although I am certainly likely to try it in the future with either thin soft steel flat stock or brass, although I like the solution I came up with for other reasons) I sawed some 1/8″ x 1″ x 1″ angle stock I had on hand.  I cut the length such that the body of the plate would be fully housed but the teeth were exposed and unfettered.

Then I cut off most of one side of the angle stock to reduce the arm of the stock from 1″ to 1/2″ so that when two pieces of the cut angle stock were placed together the configuration would be a “T”.  I used the finished plate itself to provide the layout holes into the stirrup “T” plates.  One half of each pair of the plates was drilled and tapped, the other was drilled and countersunk to fit machine bolts I had in my hardware stash.

Placing the two halves of the “T” stirrup over the pair of bolt holes in the plates, and screwing in the machine bolts, the task of mounting the plate to a stirrup was finished and it was time to move on to the bow frame (this picture is a bit out of sequence and was intended for another purpose but you get the idea).

Roubo Joinery Bowsaw Prototype


One of the many peculiarities of mid-18th Century Parisian workshops and their accouterments as documented by Roubo revolves around the absence of backsaws and panel saws in the tool kit.   These were bow saw and frame saw folks, and they used bow saws for any number of functions at the bench including stock prep and dimensioning to delicate dovetail work.  As for the panel saw, it was only mentioned in one brief sentence and then only in the context of building carpentry.  For whatever reason the French furniture and joinery shops were committed to open frame saws, whether bow saws or sash saws, as their workhorse tools.

Subsequent to my visit to Bad Axe Tools in November and the conversation it sparked about saws in mid-18th Century Parisian workshops, both Mark Harrell and I were noodling the concept of interpreting those saws for contemporary craftsmen.  I think we arrived at the same point more-or-less simultaneously, and I suggested the need for exploring bow saw prototypes based on the saw plate for the Bad Axe one-man Roubo-esque frame saws.  Mark bit and expressed immediate support.  By “support” I mean that he would provide me with some saw plates for me to try out the concept, and would fabricate custom specified plates for me to experiment with.

***A note about such a collaboration: I gladly share my knowledge and curiosities with anyone interested in pursuing the same paths I am on.  I’ve made available all the observations, opinions, and documentation I have, including detailed photographs of my own vintage saws, to anyone who asked.  In that regard I am not showing any preference for Bad Axe, they were simply the folks who asked me to engage in this exploration.***

Since I already had a Bad Axe frame saw and thus the dimensions of their standard saw plate I was able to begin fabricating a bow saw as close to Roubo’s as possible, or at least as close as I could guess.  I grabbed the saw plate, some of the ultra dense 5/4 white oak from my stash (left over from making the Studley bench top replica for the exhibit), and got to work.

The results were instructive.

Next 2018 Barn Workshop Calendar Reminder

The complete 2018 Barn workshop schedule, which I will post every couple of weeks to help folks remember the schedule.


Historic Finishing  April 26-28, $375

Making A Petite Dovetail Saw June 8-10, $400

Boullework Marquetry  July 13-15, $375

Knotwork Banding Inlay  August 10-12, $375

Build A Classic Workbench  September 3-7, $950

contact me here if you are interested in any of these workshops.

Leafy Friends Find A New Home

A few years ago my friend DrDan gifted me with four tropical hardwood tree-lings that he had grown from seed; mahogany, Chinese rosewood, sandalwood, and another that I cannot recall at the moment (padauk?).  Of those four, two remain alive but laboring in our alpine climate in the Virginia Highlands.  Despite moving them indoors in front of a large south-facing window during the winter, they struggled no matter how hard I tried caring for them.  The days here are just too short in the winter since the mountain blocks much of the sun by mid-afternoon, and the cabin too chilly.

That led me to seek out a new home for them, and my longtime friend Tred volunteered his yard in South Florida.  On a recent trip we swung by Tred’s place where these two tree-lings will be planted to mature and flourish.  I’d bet that in a hundred years we could go there and see a fine specimen of a Cuban Mahogany (sweitenia mahoganii) tree on the right alongside a Fragrant/Chinese Rosewood (“huanghuali” or dalbergia odorifera) tree on the left.  I hope they do well in the climate of south Florida, and will go back to visit them periodically.

While visiting we got a nice view of Tred’s shop, which survived the recent hurricane just fine (an ancient live oak in the yard did not fare so well).  I think the footprint is about 75 x 40 feet, and the full bank of north windows provides spectacular interior lighting.

Out front is a cool gnarly chair made from a mahogany stump.  Aesthetically intriguing but lacking in the comfort department.

Gluing Curved Panels With Roubo’s Coopering Cradles

When constructing a bowed or undulating panal or structure, one of the challenges is to decide the manner of achieving the shape.  Commonly there are main four methods employed: sculpting/carving from solid slabs, a la bombe’ chests; glued laminations (home made curved plywood); contour- sawn layers or segments glued together in a stack, sometimes called “brickwork”; or coopering, which involves the assembling of long sticks or boards that are isosceles trapezoids in cross-section (“staves”) with the legs of the trapezoid angled such that the assemblage follows a desired curve.

If you consider the forms of furniture common in Roubo’s time, it is clear that there was a need to produce large numbers of curved panels reliably and quickly.  This calls for coopering.  And, for each individual curvature/radius a unique set-up was required.  Roubo presents two distinct solutions to the problem.   The first, marked “a” in his drawing, shows a pincer/bar clamp and a group of spacer shims to align the individual staves to assure the proper configuration while the glue sets.  This approach strikes me as very finicky, and thus time consuming, to achieve standardized results.

Roubo’s preference was stated unequivocally in his commentary on Plate 102.

Before speaking of gluing curved wood, it is good to enter into the details of gluing those pieces which, although straight along their length, are only curved on their width, like panels that are curved in plane, columns, etc.

For curved panels [in plane], they hardly differ from straight ones. As to the manner of joining them and gluing them, it is only a matter of using a clamp to bring together the joints because when these same panels are a bit curved, the clamps always make them a bit more or less curved than is necessary. You remedy this by putting cauls between the panel and the clamps [bar], which is always placed at the side of the bulge, as you can see in figure 5, side a. No matter what precautions you take, the cauls that you are required to tighten or loosen twist the joints and prevent the glue from working properly. Even when the panels are thin, the clamps bend them and even break them. That is why it is much better to make cradles that you [cut] hollow in the same shape as the panel, which you join and hold in the cradle by means of a wedge, see figure 5, side b.

There must always be at least two of these cradles for gluing a panel and even three for one a bit larger. One should also observe that the angle of the hook “holding the wedges” of these cradles be a bit sharp [acute] so that the panel cannot shift when closing it, see figure 6.

I do not know how to conceal the fact that this method takes much longer and consequently is more costly than the first one because it is necessary to make as many cradles as one has of panels of different curves. These considerations should diminish the advantages that result from using these cradles. These same cradles also serve to fasten [peg] the curved work, which is always better than the clamps, which distort the joints and sometimes break curved crosspieces.


The second approach, marked “b” in the top drawing and important enough to make another detail drawing to communicate the essence of it, makes more sense to me.  In fact I have used this approach countless times beginning back in the pattern shop where we produced dozens/hundreds(?) of core boxes for creating cores for casting pipes.  Although our patterns were permanently assembled, the process is conceptually identical to using a coopering cradle.

The general process is pretty fool proof.  First, lay out the curve with a compass or trammel on a pair (or more) of wooden timbers.  Cut out the concave form.  Since these would be used for gluing it is almost certainly true that these would be slathered with wax or tallow to prevent the curved panel from being glued to the form as it is being built.

Saw as many staves as are needed for the panel being built.  On the edges of the staves plane or saw a slight chamfer so that the staves fit nicely into the curved form, with intimate gluing surfaces aligning between each stave.  This angle can be determined during the layout of the panel, and transferred with a bevel gauge.

Place the beveled staves into the form to confirm the fit.  Make sure the forms are square to each other.

Fill any extra space with loose boards, and pinch the curved panel staves together with individual or compound wedges.    If there is glue between the coopered staves, once that dries the task is finished and after knocking out the wedges the curved panel can be removed to work further.



Measurementally Challenged

It was supposed to be somewhere between “occasional flurries” up to a maximum of 1-3 inches.

Hmmm.  We ended up with nearly a foot.  It’s been a pretty light winter for snowfall, but March is definitely coming in like a lion.


Good Scores On The Road

During some recent travels I made some good acquisitions for the shop.

When I have the time and opportunity I browse through the stacks of textiles at antique shops in the hope of finding some nicely worn linens that have been used enough to no longer be stiff, but not so much as to lose their “tooth,” thus making them the preferred tool for pad finishing.  Otherwise I have to purchase new linen and run it through the washer and dryer a few times to soften it up.

The best antique store bargains are usually plain, un-embroidered table cloths with an incomplete set of napkins.  At a tiny antique shop in central Ohio I found such a package.  It was a full sized table cloth in near pristine shape, with seven napkins.  I think the price was around $15, whereas had there been eight napkins the price would have been more like $75-100.  This set will become part of my finishing rag inventory and went into the bin straightaway.

Then I found this little jewel of a turning bow saw at the SAPFM tool sale/banquet in Williamsburg during the WW18thC confrence.  My long time friend John Davis had this on his table and I snapped it up.  This petite beauty was just the right size and shape for me to use almost every day, and I will chronicle its tarting up in the coming weeks.  The only thing not perfect was the replacement paddle, and I am thinking of either ebony or ivory for that.  I am pretty certain the bow frame is beech and the handles are boxwood.

Stay tuned.

An Old Friend on T.V.

This is not a politic/economic/faith blog, and though I neither apologize nor shy from my minarchist convictions and Biblical worldview, that is generally not what is about.  That said, I was delighted to hear from my long-time friend economist Dr. Walter Williams that he was featured in a lengthy one-on-one interview on television recently (we do not have our television connected so I had to find it on line, and this video is not the best).  We will be dining together again next week and I look forward to engaging him in person as has occurred dozens of times previously in the past 30+ years.

Back to regularly expected content tomorrow.

WARNING — Snowflakes, DO NOT watch this as you will be triggered and microaggressed, and you will be unable to find a Safe Space adequate for your whimpering selves.  Walter’s views are considered radical and strident by some, but I find them morally, epistemologically and empirically sound.  Which, IMHO, is why they will not prevail.


Desk Moldings III

With the fairly straightforward triple moldings on the feet completed and my broken arm on the mend, albeit still fairly weak, it was time to move on to the double moldings on the thinner upright sections of the legs(?).  These presented the additional challenge of including sixteen inside-corner sections that could not be completed with only scratch stock cutters.

Since the scratch stock cutter for the triple moldings was also perfectly sized for the double moldings on the thinner “legs” I gave it a try but soon decided that I needed to make another scratch stock to straddle both sides tightly in order to achieve the best results.  Even so I got more chatter to the surface than I found acceptable, so in the end I wound up touching all the surfaces with rifflers.

On top of that the shape of the “legs,” and the sixteen inside corners to the molding runs left me with a fair bit of hand carving to accomplish.  I followed and extended the shoulders of the rabbet with a sharp knife and excavated them with straight carving gouges, then carved the remaining profile sections with gouges.


The final step of the moldings for this element was to carve the terminus of each molding run at the bottom of each “leg,” where they would join the feet.   It was fairly simple, I just whacked at the appropriate place with a carving gouge of the correct size and sweep, and removed the excess with a flat gouge.  Somehow I failed to take a photo of this area once it was all cleaned up, but you get the idea.

Desk Moldings II

Once the convex triple moldings were established effectively to my satisfaction the time came to cut the tiny rebate on the outer edge of the foot.  That step took a couple of tools, one a modified marking gauge and the other a very simple rebating scratch stock.


For the marking gauge, which in fact I had set up already as a slitting or cutting gauge with a sharpened knife cutter, I needed to modify the block so that the beam could follow the radius as the contour swept in and/or out along the outside of the element.  The intricate technology required for this modification is no doubt intimidating, but it was really nothing more complicated than sawing a 1-inch dowel in half and adhering it in place with double stick tape.  I also relieved the shoulders of the gauge block to allow for even tighter turning, which would be needed for the leg moldings.

This allowed me to scribe the inner shoulder of the undulating rebate with little effort.

The follow-up tool was a scratch stock fashioned from a piece of tropical hardwood flooring with a tiny rectangular exposure that scraped out the rebate perfectly.  On the first foot I cut the three convex beads first followed by the rebate.  After that I reversed the order of the process.

The end result was satisfactory.

Then I broke my right arm and was out of commission for another few months.  See what I meant about the client’s patience?